Fix clang compiler warnings on FreeBSD in erts

The following are deliberately left, as I have only a list of compiler
warnings and no system to test on:
hipe/hipe_x86_signal.c:264:5: warning: no previous prototype for function '_sigaction' [-Wmissing-prototypes]
int __SIGACTION(int signum, const struct sigaction *act, struct sigaction *oldact)
    ^
hipe/hipe_x86_signal.c:222:21: note: expanded from macro '__SIGACTION'
                    ^
1 warning generated.
sys/unix/sys_float.c:835:16: warning: declaration of 'struct exception' will not be visible outside of this function [-Wvisibility]
matherr(struct exception *exc)
               ^
sys/unix/sys_float.c:835:1: warning: no previous prototype for function 'matherr' [-Wmissing-prototypes]
matherr(struct exception *exc)
^
2 warnings generated.
drivers/unix/unix_efile.c:1504:11: warning: implicit declaration of function 'sendfile' [-Wimplicit-function-declaration]
        retval = sendfile(in_fd, out_fd, *offset, SENDFILE_CHUNK_SIZE,
                 ^
1 warning generated.

1 files changed, 1 insertions, 1 deletions

diff --git a/erts/lib_src/common/erl_printf_format.c b/erts/lib_src/common/erl_printf_format.c
index fd25cce7ed..384b1b1ad7 100644
--- a/erts/lib_src/common/erl_printf_format.c
+++ b/erts/lib_src/common/erl_printf_format.c
@@ -339,7 +339,7 @@ static int fmt_double(fmtfn_t fn,void*arg,double val,
     double dexp;
     int exp;
     size_t max_size = 1;
-    size_t size;
+    int size;
     int new_fmt = fmt;
     int fpe_was_unmasked;